Code Division Multiple Access (CDMA) provides a method for transmitting simultaneous signals over a shared portion of the transmission spectrum. CDMA's spread spectrum technique generally overlaps transmissions on the same carrier frequency, by assigning a unique code to different conversations. After a speech codec (for example, a hardware circuit or software routine) converts voice signals to digital signals, CDMA generally spreads the voice stream over the full bandwidth of the CDMA channel, and separately codes the various data blocks making up the stream so that they may be decoded at the receiving end. In this way, different voice conversations may use the full bandwidth of a data channel at the same time. Wideband-CDMA, hereinafter referred to as “WCDMA” is a Third Generation (3G) technology that increases data transmission rates in GSM systems by using the CDMA air interface instead of Time Division Multiple Access (TDMA).
One sequence for a data block transfer using the WCDMA standard may include, for example, encoding/decoding a data block or stream from/to MAC and higher layers, to offer transport services over the radio transmission link. The channel-coding scheme may generally be a combination of error detection, error correcting, rate matching, interleaving and transport channels mapping onto and/or splitting from physical channels, thereby providing various data block format types.
To avoid transmitting too much information, however, the WCDMA standard in some cases does not provide the receiving units, such as, for example, mobile handsets, with precise information regarding the transmitted data block format. In such a case a mobile handset, for example, may have to determine which format, out of a predetermined set of possible formats, was transmitted, to decode the received data. The user equipment (for example a handset) generally chooses between possible formats that include the same coding scheme and Cyclical Redundancy Checking, hereinafter referred to as “CRC”. These formats may generally be differentiated by the size of the transport blocks and/or the number of transport blocks transmitted.
According to the CDMA standard, data transfer may be transmitted in blocks of various formats, generally related to the amount of data being transmitted. For example, voice signals may differ according to the speech intensity that generated the signal. Discontinuous Transmission bits, hereinafter referred to as “DTX”, which may be added to a data block to generate a standard size block (for example, by adding zero signals to equalize transmission sizes), may be used. Transport Format Combination Indicator bits, hereinafter referred to as “TFCI” are generally used to indicate voice signal format types. However, TFCI bits may not be sent in all cases, in which case it may not be known which format was sent, and may, for example, present a problem for decoding the data block.
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